the gauge i bought allows you to wire directly into the OEM sensor, which can be done from inside the engine bay, or by tapping the wire on the backside of the gauge cluster. The same wire that controls the oem temp gauge on the cluster can be tapped to control the aftermarket gauge. It will just read out an temp display instead of a little needle that sweeps from "C" to "H" and you figure your all set if it stays in the middle but you dont really know what the actual temp is lol